The movement of certain electrically-operated valves, such as certain fuel injectors, comprises a needle that is reciprocated axially within the interior of the valve's body in response to electrical energization and de-energization of an associated electro-mechanical actuator to thereby selectively open and close a flow path through the valve. The needle is guided by an upper needle guide and a lower needle guide which are disposed spaced apart in a through-bore of a valve body member. These needle guides are essentially flat circular washers.
For assuring proper operation and avoiding leakage when the flow path is closed, the alignment of the upper and lower needle guides is critical. Lack of precision in alignment and guidance of the needle is apt to lead to a loss of performance. For example, objectionable leakage or needle jamming may result if alignment of the needle guides and their fit to the needle are not precisely controlled. Burnishing the I.D. of the upper needle guide improves precision of the fit of the needle to the upper needle guide.
The process of manufacturing the fuel injector comprises machining the through-bore of the valve body member so as to insure substantial concentricity of respective cylindrical axial surfaces within which the respective needle guides are to be disposed. Also machined to insure their perpendicularity to the co-axis of these cylindrical axial surfaces are respective circular radial surfaces which adjoin the respective cylindrical axial surfaces and against which the respective needle guides are to be disposed. Enough diametral clearance between the O.D. of the upper needle guide and the cylindrical axial surface within which it is disposed in the valve body through-bore is provided to allow the upper needle guide to float radially as it is being aligned. Once it has been aligned, its I.D. is burnished, and then it is staked in place on the valve body member.
In accordance with the invention, the apparatus includes relatively movable upper and lower portions that are operated closed and then opened. The lower portion has a fixture comprising means for aligning the valve body member to the apparatus and means for aligning the upper needle guide to the cylindrical axial surface of the valve body member that is subsequently to receive the lower needle guide. The upper portion has a tool means that performs multiple functions, one, a burnishing tool to burnish the I.D. of the upper needle guide once the latter has been aligned by the lower portion of the apparatus, two, a crimping tool to crimp the valve body member to the aligned and burnished needle guide, and three, a spring-loaded stripper that holds the upper needle guide on the valve body member during the crimping operation and that holds the assembled upper needle guide member and valve body member against the lower tooling portion while the burnishing tool is being retracted.
The invention, and the features, advantages, and benefits that characterize it, are disclosed in the following detailed description of a presently preferred embodiment that illustrates the best mode for carrying out the invention. The description is accompanied by drawings.